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Homework Help: Momentum of a proton in de Broglie wavelength

  1. Oct 19, 2012 #1


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    1. The problem statement, all variables and given/known data

    In quantum mechanics the de Broglie wavelength of an object depends
    on its momentum according to λ=h/p where h is Planck's constant.
    Protons of charge e and mass m are accelerated from rest through a
    potential V. What is their de Broglie wavelength?

    A) [itex]2h/\sqrt{}meV[/itex]
    B) [itex]h/\sqrt{}2meV[/itex]
    C) h[itex]\sqrt{}meV[/itex]
    D) [itex]h/eV[/itex]

    2. Relevant equations

    I don't know.

    3. The attempt at a solution

    I just don't know what I have to search for to solve it.
    How can I express p with e and V?
  2. jcsd
  3. Oct 19, 2012 #2
    Hello there.
    As you probably know p=mv. From conservation of energy u have mv^2/2 = eU, here you can solve for the velocity v. After that you can use it to end up with answer B)
  4. Oct 19, 2012 #3


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